1. Field of the Invention
The present invention relates to an ink jet ink, a method for producing ink jet ink, an ink jet recording method and an ink cartridge.
2. Related Background Art
An ink jet recording method is a recording method of applying a small ink droplet to any one of recording media such as plain paper, glossy media and the like to form an image, and has become rapidly widespread owing to reduction in its costs and improvement in its recording rate. In addition to improved quality of the recorded image, and concurrently with the rapid spread of digital cameras, users of ink jet printers now demand to output recorded matter which are comparable to a silver halide photograph.
As a necessary requirement for a recorded matter which is obtained from an ink jet recording method and is comparable to a silver halide photograph, it is cited that both high image density and durability of the obtained recorded matter are realized simultaneously. In particular, increasing the image density of a recorded matter obtained using black ink is important in order to provide a recorded matter comparable to a silver halide photograph. Compared with silver halide photographs, a recorded matter obtained from a conventional ink jet recording method has especially low durability (ozone resistance, in particular), and when exposed for a long period of time to factors such as light, humidity, heat and environmental gas present in the air, the coloring material on the recorded matter would deteriorate. There has been, therefore, a problem in that such recorded matters were susceptible to varying in color tone and fading of the image. Of the above-mentioned environmental gas, deterioration of the recorded matter from ozone is a particular problem.
To resolve the above-described problems, especially those of color tone and fading by ozone gas, inks which comprise a specific coloring material have been proposed (e.g. see Japanese Patent No. 02919615 and Japanese Patent Publication No. H08-26263).